This invention relates to planar transferred electron devices (TED) and more particularly to signal processing apparatus utilizing such transferred electron devices. Transferred electron devices are also referred to as Gunn devices. Planar transferred electron logic devices (TED) offer switching speeds on the order of 20 to 50 pico-seconds with delay-dissipation products of 1 to 2 pico-joules. Such speeds are not possible with CMOS (Complementary MOS) or ECL (Emitter Coupled Logic) devices. Such planar transferred electron devices are particularly useful for performing gigabit rate signal processing, Fast Fourier Transforms, etc.
Basically, TED logic devices comprise a body of transferred electron effect material such as gallium arsenide. This material has a length, thickness and doping density such that the body is characterized by a transfer of electrons from a high to a low mobility sub-band and the formation of domains in the presence of a proper biasing potential above threshold. Such devices usually have a product of length times the doping density or nl product greater than 1 .times. 10.sup.13 cm.sup.-.sup.2 and a doping density times thickness that is greater than 1 .times. 10.sup.12 cm.sup.-.sup.2. A cathode terminal is located on the top surface of the body near one end and an anode terminal is located on the top surface of the body near the end opposite the cathode end.
In the prior art devices, the biasing potential across the cathode and anode terminal is determined in the quiescent state at a value slightly below that of threshold. A typical device is operated from 0.9 to 0.95 times threshold. A gate electrode is located close to the cathode. When input signals applied to the gate electrode are of sufficient magnitude to increase the value of the electric field above that of threshold, domains are formed and the device changes state from a relatively high current state to a low current state. Since the biasing voltage in the quiescent state must be 0.9 to 0.95 times threshold, the power dissipation in such a device is considerable, for example (from 100 - 200 milliwatts). Also, small noise signals and fluctuations in the biasing voltage can cause false triggering of the device into the lower current state.